In general, vehicle systems comprise, among other items, a fuel tank fitted with a filler neck, a variety of fuel valves, a tubing for supplying fuel to the ignition system and a fuel vapor treating system (typically a carbon filter recovery system canister) to which fuel vapor from the fuel tank flows and is then used for enriching the fuel mixture fed to the ignition system.
Fuel fluid (in form of liquid, droplets, spray and vapor) from the fuel tank flows via the one or more valves, which are connected via suitable tubing, to a liquid trap intermediate the fuel vapor recovery and the tank.
The liquid trap receives fuel fluid flowing from the fuel tank which flows via the one or more valves, which flows at a relatively high velocity owing to pressure and temperature changes, and thus vapor flowing from the fuel tank carries along with it also a considerable amount of liquid fuel in the form of droplets (as a result of venturi effect). The liquid trap entraps the liquid fuel and allows fuel vapor flow towards the vapor recovery system. The liquid fuel then returns back to the fuel tank, upon pressure decrease within the fuel tank.
The document DE 100 52 399 A1 discloses a vehicle's fuel system comprising a fuel tank, at least one fuel venting valve, a fuel recovery system and a liquid fuel trap extending between the at least one fuel valve fuel valve and the liquid fuel trap, said liquid fuel trap comprising a housing formed with a confined space with at least one inlet port connectable to the corresponding at least one fuel venting valve, an outlet port connectable to the fuel vapor recovery system, and a liquid fuel discharge assembly for discharging liquid fuel into the fuel tank, said liquid fuel discharge assembly fitted with a fuel propelling mechanism.
A liquid fuel trap is important in those cases where the various valves fitted within the tank are internally installed, i.e. do not project from an upper wall of the tank, where siphons may be generated at tubes connecting to the valves to the liquid trap. Such siphons interfere with venting the tank on the one hand and, on the other hand, interfere with draining of the devices.
From U.S. Pat. No. 6,860,286 B2 a liquid fuel trap is known, comprising a housing formed with a confined space with at least one inlet port connectable to a corresponding fuel valve, an outlet port connectable to a fuel vapor recovery system, and a liquid fuel discharge valve adapted for discharging liquid fuel from the confined space into the tank. The housing further comprises a connecting arrangement for attaching the device on an inner surface of an upper wall of the fuel tank. Liquid flow from at least one inlet port is prevented from direct flowing or splashing to the outlet port. This effect may also be achieved by designing the at least one inlet port and the outlet port at different levels and axially diverted, i.e. not axially extending. Thus, the confined space may be formed with several unleveled chambers, where the inlet and outlet ports are fitted at different levels.
Such an arrangement could be used to prevent liquid fuel from getting out of the tanks venting system into the carbon canister in angle scenarios, this means situations like acceleration/deceleration of the vehicle and situations resulting in lateral and elevational liquid fuel displacement within the fuel tank (e.g. also by tilt of the vehicle).
The disadvantage is, that such an arrangement is quite complex and therefore cost-intensive.